(a) Field of the Invention
The present invention relates to a pen and, more particularly, to a puzzle pen, which allows the user to play a picture puzzle.
(b) Description of the Prior Art
The penholder or barrel of a conventional writing implement, for example, a ballpoint pen, pencil, marker or color pen, has a fixed design, i.e., a user cannot change the outer design of the penholder or barrel of a writing implement. A writing implement of fixed outer design is monotonous.
U.S. Pat. No. 6,739,780, filed by the present inventor on Sep. 29, 2003, discloses a pen that has a plurality of ornamental rings that are rotatable individually to change the outer appearance of the penholder.
U.S. Pat. No. 6,966,717, filed by the present inventor on May 18, 2005, discloses a pen having a variable penholder. According to this design, a spring retainer is provided at one end of the penholder to hold ornamental rings against one another. When released from the spring retainer, the ornamental rings can be rotated to change the combination.
The aforesaid two prior art designs allow the user to rotate the ornamental rings individually so as to further change the outer appearance of the penholder. However, these two prior art designs do not allow the user to shift movable parts in longitudinal direction along the length of the penholder.